Old animation with aliens kidnaps humans...

I mostly remember a scene and nothing else of it.
It's an animation from 80's I think. Maybe it's anime, maybe it's not. I remember it to be somehow similar to Heavy Metal 1981.

The scene I remember:
Some aliens catch/kidnap an old man and young girl with some lights. They two get teleported into some tubes, where they transform. The girl becomes way bigger and muscular (I think with red hair) while the old man becomes mechanical almost like a robot. Maybe and girl gets some mechanical part, arm, or leg I'm not sure. The two latter fights I think in some arena.

Does this sound familiar to anyone?